Is the ocean carbon sink sinking?

The past few weeks and years have seen a bushel of papers finding that the natural world, in particular perhaps the ocean, is getting fed up with absorbing our CO2. There are uncertainties and caveats associated with each study, but taken as a whole, they provide convincing evidence that the hypothesized carbon cycle positive feedback has begun.

Of the new carbon released to the atmosphere from fossil fuel combustion and deforestation, some remains in the atmosphere, while some is taken up into the land biosphere (in places other than those which are being cut) and into the ocean. The natural uptake has been taking up more than half of the carbon emission. If changing climate were to cause the natural world to slow down its carbon uptake, or even begin to release carbon, that would exacerbate the climate forcing from fossil fuels: a positive feedback.

The ocean has a tendency to take up more carbon as the CO2 concentration in the air rises, because of Henry’s Law, which states that in equilibrium, more in the air means more dissolved in the water. Stratification of the waters in the ocean, due to warming at the surface for example, tends to oppose CO2 invasion, by slowing the rate of replenishing surface waters by deep waters which haven’t taken up fossil fuel CO2 yet.

The Southern Ocean is an important avenue of carbon invasion into the ocean, because the deep ocean outcrops here. Le Quere et al. [2007] diagnosed the uptake of CO2 into the Southern Ocean using atmospheric CO2 concentration data from a dozen or so sites in the Southern hemisphere. They find that the Southern Ocean has begun to release carbon since about 1990, in contrast to the model predictions that Southern Ocean carbon uptake should be increasing because of the Henry’s Law thing. We have to keep in mind that it is a tricky business to invert the atmospheric CO2 concentration to get sources and sinks. The history of this type of study tells us to wait for independent replication before taking this result to the bank.

Le Quere et al propose that the sluggish Southern Ocean CO2 uptake could be due to a windier Southern Ocean. Here the literature gets complicated. The deep ocean contains high concentrations of CO2, the product of organic carbon degradation (think exhaling fish). The effect of the winds is to open a ventilation channel between the atmosphere and the deep ocean. Stratification, especially some decades from now, would tend to shut down this ventilation channel. The ventilation channel could let the deep ocean carbon out, or it could let atmospheric carbon in, especially in a few decades as the CO2 concentration gets ever higher (Henry’s Law again). I guess it’s fair to say that models are not decisive in their assessment about which of these two factors should be dominating at present. The atmospheric inversion method, once it passes the test of independent replication, would trump model predictions of what ought to be happening, in my book.

A decrease in ocean uptake is more clearly documented in the North Atlantic by Schuster and Watson [2007]. They show surface ocean CO2 measurements from ships of opportunity from the period 1994-1995, and from 2002-2005. Their surface ocean chemistry data is expressed in terms of partial pressure of CO2 that would be in equilibrium with the water. If the pCO2 of the air is higher than the calculated pCO2 of the water for example, then CO2 will be dissolving into the water.

The pCO2 of the air rose by about 15 microatmospheres in that decade. The strongest Henry’s Law scenario would be for the ocean pCO2 to remain constant through that time, so that the air/sea difference would increase by the 15 microatmospheres of the atmospheric rise. Instead what happened is that the pCO2 of the water rose twice as fast as the atmosphere did, by about 30 microatmospheres. The air-sea difference in pCO2 collapsed to zero in the high latitudes, meaning no CO2 uptake at all in a place where the CO2 uptake might be expected to be strongest.

One factor that might be changing the pressure of CO2 coming from the sea surface might be the warming surface waters, because CO2 becomes less soluble as the temperature rises. But that ain’t it, as it turns out. The surface ocean is warming in their data, except for the two most tropical regions, but the amount of warming can only explain a small fraction of the CO2 pressure change. The culprit is not in hand exactly, but is described as some change in ocean circulation, caused maybe by stratification or by the North Atlantic Oscillation, bringing a different crop of water to the surface. At any event, the decrease in ocean uptake in the North Atlantic is convincing. It’s real, all right.

Canadell et al [2007] claim to see the recent sluggishness of natural CO2 uptake in the rate of atmospheric CO2 rise relative to the total rate of CO2 release (from fossil fuels plus land use changes). They construct records of the atmospheric fraction of the total carbon release, and find that it has increased from 0.4 back in about 1960, to 0.45 today. Carbon cycle models (13 of them, from the SRES A2 scenario) also predict that the atmospheric fraction should increase, but not yet. For the time period from 1960 to 2000, the models predict that we would find the opposite of what is observed: a slight decrease in the atmospheric fraction, driven by increasing carbon uptake into the natural world. Positive feedbacks in the real-world carbon cycle seem to be kicking in faster than anticipated, Canadell et al conclude.

There is no real new information in the Canadell et al [2007] analysis on whether the sinking sink is in the ocean or on land. They use an ocean model to do this bookkeeping, but we have just seen how hard it is to model or even understand some of the observed changes in ocean uptake. In addition to the changing ocean sink, drought and heat wave conditions may change the uptake of carbon on land. The infamously hot summer of 2003 in Europe for example cut the rate of photosynthesis by 50%, dumping as much carbon into the air as had been taken up by that same area for the four previous years [Ciais et al., 2005].

The warming at the end of the last ice age was prompted by changes in Earth’s orbit around the sun, but it was greatly amplified by the rising CO2 concentration in the atmosphere. The orbits pushed on ice sheets, which pushed on climate. The climate changes triggered a strong positive carbon cycle feedback which is, yes, still poorly understood.

Now industrial activity is pushing on atmospheric CO2 directly. The question is when and how strongly the carbon cycle will push back.
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[Response: I think I understand your question now. My feeling is that all is not lost. What we are seeing is reduced carbon uptake by the natural world, not an actual CO2 release from the natural world yet. David]

i was wondering, when reading Canadell et al, about the strong interannual variability of the terrestrial carbon sink: as it is the remainder of the “emissions – airbourne fraction” term and the calculated ocean uptake, it reflects more or less the variability of the airbourne fraction.

Now do global vegetation models simulate this strong variability, when forced with observed climate (i would think this would be a good test, both for models and for the way carbon sinks are calculated) ?

is this variability somehow related to Nino events, volcanic events, or anything like that ?

Thanks –

[Response: Don’t take this as an authoritative answer, but my hunch is there’s a lot of noise in the terrestrial sink, which is all done by difference. I suspect there may be variability in ocean carbon fluxes that models don’t simulate. The land gets blamed for everything we don’t understand. I could be wrong about this. David]

— CO2 dissolving into the ocean as ions (raising pH) that ought to go on til it’s in equilibrium with the atmosphere, wherever that level ends up, right?
—- actual removal from dissolved CO2 — being ‘sunk’ out of the oceans (as by calcite and aragonite shells from plankton sinking into sediment, long term removal from cycling back to the atmosphere)?

I know in some deep water where CO2 levels are higher, the calcite and aragonite do end up dissolving back into the ocean water even now. There’s a depth below which that always happens, and that can change as levels in the ocean of dissolved CO2 increase and pH increases.

[Response: Wow, finally you ask a question, Hank, that I’m competent to answer! CO2 dissolves in the ocean mostly be reacting with dissolved carbonate ion, CO3(2-), to form bicarbonate, HCO3-. This will continue happening, but the concentration of carbonate ion decreases as CO2 rises, so seawater loses its buffer strength. The response of CaCO3 is to dissolve, replenishing the carbonate ion. Fossil fuel CO2 can’t deposit as CaCO3 without a source of base, from weathering igneous rocks, which takes hundreds of thousands of years. Or deliberate chemical treatment is possible, speeding up the process. David]

I read this site regularly, although I have no science background. So I’m pretty hesitant to comment. But this especially sounds so dire. How much do you, as scientists steeped in this research, feel that human life on this planet has a fragile future at best? (I realize this is a broad question, so if it’s not applicable, please delete it.)

this is a very helpful essay -let for the non atmospheric scientist.
I hope for more of these, on the subject of the ocean atmosphere interface and for more extended comments by those better read than myself

Do we know offhand if there’s been a change to the level of calcium carbonate? I ran across a paper a few days ago (forgot to save a link) explaining how reduced CaCO3 tends to increase the partial pressure of CO2. Could erosion control during the last century have reduced the amount of calcium (and magnesium) oxides and carbonates entering the ocean? Could this be part of the reason?

[Response: CO2 reacts with dissolved CO3(2-) in the water, and that in turn provokes CaCO3 to dissolve. I don’t know if an extra dissolution signal has been detected yet, however. David]

How do photosynthesizing organisms such as phytoplankton fit into the picture?

Also, to explicate Shannon’s question: Much has been made of 450 ppm as a threshold beyond which Very Bad Things will probably happen. Shannon is asking (more or less) “Are we already there?”

[Response: Ocean biology, if it were to continue unaffected by the changing circulation, temperature, or pH, would have no effect on fossil fuel CO2 because it was sending carbon to the deep sea, and it would continue. But if the biology changes in some way, it would affect ocean uptake. One possibility is reduced formation of CaCO3 by surface ocean algae and corals. This would accelerate the absorbtion of CO2 a little bit. David]

I think Shannon means, are we seeing a carbon sink saturation/slowdown much earlier than anticipated, i.e. not by 2050 at 450 ppm CO2e as some predictions have it, but 2007 at 380 ppm CO2e. Perhaps yet further evidence that feedbacks are kicking in more rapidly than anticipated just a few years ago.

[Response: Everyone seems to have understood Shannon’s question except for me. I still don’t know the answer, though. Forecasting the carbon cycle seems to be a tricky business. David]

I think Canadell is a very important piece, in part because it quantifies the recarbonization of the energy system and in part because it shows that emissions are rising faster than the IPCC’s fastest-growing computer model scenario–even the one that was not included in the latest report because scientists thought it was unrealistically high. I blogged on it here:

I read several weeks ago that the waters off the N. American NW Pacific coast from Oregon to Alaska have become too acidic. This includes not only dissolved CO2, but nitric and sulfuric acids from the atmosphere & water pollution.
As a paleontologist(retired), I can add that the geological record contains strong evidence of several events coupled w/GW of oceans reaching their CO2 retention capacity, in which increased acidification along continental selves & near-shore environments led to widespread invertebrate extinctions. Many benthic organisms in particular are affected because they can no longer produce calcium carbonate.
Increased acidification & the inevitable dramatic decrease in dissolved oxygen no doubt put all marine organisms at risk of extinction. The overall effect being extensive eutrification creating anoxic comditions extending to the continental shelves. Such events have accompanied many mass extinction events.
Thus, the present increased acidity in conjunction w/increasingly common & enlarging Dead Zones along continental shelves from polluted stream water are putting the oceans in extreme peril. If the oceans, being the global food chain base, ‘die’, this will inevitably lead to terrestrial extinctions.
These feedback effects on the marine biosphere, rapidly spreading drought, groundwater depletion, salt water intrusion & stream pollution are *The Most Serious consequences of GW*. These problems are already in motion & must be addressed immediately. Not to minimize the disasterous consequences of sea level rise-especially for Eurasia, but sea levels rise gradually. This gives many coastal communities time to adjust by infrastructure reconstruction & rezoning, compared to the consequences of losing water & food from the former. It’s ALL About Ocean Health & Water.
As Kelvin Rudolfo of U of I, Chicago (the finest lecturer & field instructor I’ve ever known & with whom it was an honor to have been a grad assistant) once concluded in a dramatic, moving undergad lecture on GW in the 70s: “What does all this mean?….Learn to Farm!”.

Sidd, “what does outcrop mean?” — here it means deep ocean water rising up to the surface — and “deep ocean” means water that sank to the depths long ago, at least a century, perhaps up to a thousand years ago. How long it takes for the ocean to circulate is still being figured out.

The paper I mentioned was actually a chapter of Greenhouse Gas Sinks Edited by D Reay, University of Edinburgh, UK; N Hewitt, University of Lancaster, UK; J Grace, University of Edinburgh, UK; K A Smith.

It’s not quite Henry’s law since pCO2 from the ocean also varies with [H(+)]^2 and that mean small changes in pH can set off decarbonization of the upper ocean. Local changes in pH could have a significant effect.

[Response: Henry’s law applies to the dissolved CO2 species, and also, in this case, to the hydrated form of CO2, carbonic acid, H2CO3. These two species are lumped together into what is called H2CO3* as an operational thing because it is difficult to measure the proportions of the hydrated and unhydrated forms. The expression for Henry’s law is that pCO2 / H2CO3* = a constant KH. The constant is very sensitive to temperature, somewhat to salinity. The relative concentrations of the other forms of carbon, bicarbonate (HCO3–) and carbonate ion (CO32-) are controlled as you say by the acidity of the seawater solution and the dissociation constants for carbonic acid K1 and K2. All these K’s are equilibrium constants, they just have different names by convention. Semantically, the pH behavior is not called Henry’s law, but you are absolutely correct that changing the pH has a huge effect on the amount of CO2 that wants to come out into the gas phase. Acidify seawater completely and it would foam like beer. David]

As this is one of the $64,000 questions in terms of how this will all pan out, I wonder, if you have the time, if you could give a few references of your selelection the better published articles on this question, however limitted the conclusions.

[Response: My own latest thoughts on the topic are here. No single mechanism can do the entire CO2 drawdown by itself, we resorted to a “stew” of ideas. An earlier review paper of the conundrum is here. David]

The comment above is worth repeating:Increased acidification & the inevitable dramatic decrease in dissolved oxygen no doubt put all marine organisms at risk of extinction. The overall effect being extensive eutrification creating anoxic comditions extending to the continental shelves. Such events have accompanied many mass extinction events.

The offshore low oxygen zone in the Eastern North Pacific off of Oregon is one example. This has been going on for six consecutive years and may very well become a permanent feature.

By the way, this is yet another argument against ocean iron fertilization as a means of generating carbon offsets for the cap-and-trade carbon market. Assisting in the eutrophication of the oceans is a very bad idea!

Regarding the methane from lakes in Siberia, here’s the Nature paper:
Letter

They radiocarbon-dated the methane and found that the last time those carbon atoms were in the atmosphere was around 30-40,000 years ago. The conclusions of their paper are as follows:

“In conclusion, we have shown that North Siberian lakes are a significantly larger source of atmospheric CH4 than previously recognized. Emissions are dominated by ebullition, a mode of emission that we have quantified using the new technique of mapping bubbling point sources. This CH4 source is largely fuelled by thermokarst, and we have linked the expansion of thaw lakes during recent decades with a 58% increase in lake CH4 emissions, demonstrating a new feedback to climate warming. Though the recent increase in flux due to lake expansion is modest relative to anthropogenic emissions, the 500 Gt of labile Pleistocene-aged C in ice-rich yedoma permafrost could greatly intensify the positive feedback to high-latitude warming by releasing tens of thousands of teragrams of CH4 through ebullition from thermokarst lakes if northeast Siberia continues to warm in the future, as projected.”

If, say, half of that 500 GT of carbon in the permafrost ends up in the atmosphere, that would be the equivalent of about 80 years of anthropogenic CO2 emissions at today’s rates. How fast would that happen? No idea. How long will it take to melt the Greenland ice sheet at current forcings? Melt it will, but how fast? 100 years? 1000 years?

The sane response to such uncertainties is to eliminate the use of fossil fuels asap and replace them with renewable energy sources.

Rephrase: Are we seeing some of the predicted effects at 380 PPM that we expected to see at 450 PPM?

[Response: I’m not real up on the details of what the carbon cycle models, in particular the terrestrial biosphere carbon cycle models, predicted about when they’d start releasing co2 rather than taking it up. I don’ think those models are very well grounded in observations, just my opinion. I guess the turnaround though is happening faster than they predicted. David]

Changes in ocean circulation are not only going to kill a lot of sea life, but there is positive feedback again on greenhouse gas and warming acceleration … and the ‘closing of the door’ on for ever on the solution of using sea ecosystems to sink the carbon back where it came from, living bionmass in thriving oceans [as distinct from our largely dead and dying ones]

… but as if that currently almost half-complete death of the base of sea life [corals and phytoplankton] , there is something people do not seem even be aware of let alone to have modelled, the methane hydrate distribution on continental shelves is controlled by ocean temperature LOCALLY … just changing the ocean circulation at almost any coastline can trigger massive methane release without any increase in average earth temperature!

… the amount of methane is potentially so massive that it could even swamp the breakdown of methane in the atmosphere with sudden massive acceleration in warming due to methane persisting far longer

… in any case we shall never be able to recover from this input because it triggers warming and then the rest of the methane will be released as well and its likely all over … thermal run-away

life is demonstrably not coping with the current rate of change, measurements suggest it is four times the maximum rate at which many species are changing their location and habits in failing attempts to adapt… we have not the time to sit around just talking any longer, we need things back under control in all-out emergency action , it is simply irrational to find out what we overlooked after it commits us all to slow death …

The pictures painted to decision makers are of a sort of trade-off between cost and inconvenience of change as against temperature rise and some damage to nature [some say 50% by 2050, some say sooner] … no-one seems to be pointing out that one cannot damage nature 50% and it stop there, by that stage we have committed ourselves to almost complete death of the planetary life system and ourselves with it…

The ‘fiddling whilst Rome burns’ analogy comes to mind… we know the atmosphere is disturbed, we know we are disturbing the sea circulation…. it really is time that all these things were reducing, not accelerating in positive feedback already ,out of control ,as the figures indicate they are …

it is not time for another five years research before acting , it is time to mobilise everyone on the planet to change our way of life [one of the biggest ‘inertias’ in the system is humanity’s reluctance to change and learning time of new ways] …

It is seriously time to stop playing brinkmanship with existence of life on earth …and that is the thing we are gambling with against what is currently, but briefly a fairly small expense in best prudent insurance now [compared to massively increasing cost as time goes on, until no amount of money can save the ecosystems and us at a time which may easily be not far ahead , some say it is here already … there is absolutely no justification for risking all life on this planet for even massive expense, but we may well have a tiny window for doing it cheaply whilst the seas are somewhat alive … their death is not linear in time either …

We simply cannot have time for the mistake some dozen groups are playing with of just creating algal blooms which must then die , depriving the ocean of oxygen and with no great sequestration of CO2 to deep deposits or even guarantee that more co2 will not be released long term…

It is a crude sledgehammer approach where a hundredth of the amount of iron used could be chelated and fed in slow-release to the oceans to let the ecosystems expand, saving the seas and sinking truly massive amounts of CO2 into living biomass as the seas exponentially grow back to life UNDER OUR CONTROL and monitoring…

We even get vastly more food out of the process to offset the cost , enough to feed all people at last and at low cost , and off-setting the crippling loss of fertility of the land from modern farming methods…

If we all plant trees on our land , we can do much the same on the land too…

A serious look at the motor car shows that we would actually live vastly healthier lives without it and its pollution even without the massive contribution stopping using petrol and diesel cars would be to bringing things under control… this really is a win-win situation , a no-brainer … helping the earth and improving our quality of life at the same time…

Why are people not doing this? Do they not know yet? It seems even politicians mostly do not know that we are accelerating down the slippery slopes already , nor appreciate the extent of the damage , so how can the people ?

I just do not understand either how when we know that we don’t know all that could go wrong ,that we don’t play prudent and safe, extra-cautious until we do know , when we are playing for stakes of almost all life on earth, our own existence…

We are not then even considering the worst case scenarios and then maximising the chance of avoiding them, but why not? Since we all die in those cases, surely they are to ones to consider and ensure we maximise chances of avoiding them …

What we have at present i think is that even the best policy on the table is of somewhat less than 50% chance of keeping below 2C … but 2C is the point where some believe thermal run-away sets in… that makes no sense then at all as a policy, we want a close to zero chance of getting to that 2C point, not for it being more likely than not!

Again, methane release in the sea is being reported off South America, let us hope that it is only very local vulcanism or sea-bed shift , because if it is not we likely are too late to stop the ‘clathrate gun’ being triggered by ocean current changes kicking it off by merely LOCAL temperature rise over massive methane hydrate deposits … caused by just any ocean current shift with no average temperature rise of the earth needed to make it kick in…

I just do not get the confidence that men imagine that we can control this whenever we like , we really do not know that!

and the cost of doing so when we finally do so is exponentiating as we speak , what point is there at all in not doing all that can be done now, immediately ???

Equally we cannot just sit around and let the seas die, if we let 50% of species die off on the planet currently predicted , then it doesn’t stop there! … take any key organ out of our body and the whole dies, lose any key species and the ecosystem dies , almost all of it , and then we ourselves cannot survive that… the ecosystem that feed us will be committed to death long before v50% of species are extinct … putting it as percentage is misleading, this is NOT a linear process at all,not even close …

How can mankind not be working flat out to absolute first priority to minimise the chance of that, by every single method we know …I just don’t understand our complacency at all … we pride ourselves on intelligence , but this matter makes people dumb as rabbits caught in the headlights , standing inactive in the path of an approaching truck…

There is so much we can get going on immediately to get things moving back toward control, out of positive feedback and it just isn’t even beginning to happen… instead we are not even aiming to give ourselves half a chance to avoid pushing nature to the edge where there is no return…

It is less than imprudent, it is irrational in extreme … Changes in ocean circulation are not only going to kill a lot of sea life, but there is positive feedback again on greenhouse gas and warming acceleration … and the ‘closing of the door’ on for ever on the solution of using sea ecosystems to sink the carbon back where it came from, living bionmass in thriving oceans [as distinct from our largely dead and dying ones]

… but as if that currently almost half-complete death of the base of sea life [corals and phytoplankton] , there is something people do not seem even be aware of let alone to have modelled, the methane hydrate distribution on continental shelves is controlled by ocean temperature LOCALLY … just changing the ocean circulation at almost any coastline can trigger massive methane release without any increase in average earth temperature!

… the amount of methane is potentially so massive that it could even swamp the breakdown of methane in the atmosphere with sudden massive acceleration in warming due to methane persisting far longer

… in any case we shall never be able to recover from this input because it triggers warming and then the rest of the methane will be released as well and its likely all over … thermal run-away

life is demonstrably not coping with the current rate of change, measurements suggest it is four times the maximum rate at which many species are changing their location and habits in failing attempts to adapt… we have not the time to sit around just talking any longer, we need things back under control in all-out emergency action , it is simply irrational to find out what we overlooked after it commits us all to slow death …

The pictures painted to decision makers are of a sort of trade-off between cost and inconvenience of change as against temperature rise and some damage to nature [some say 50% by 2050, some say sooner] … no-one seems to be pointing out that one cannot damage nature 50% and it stop there, by that stage we have committed ourselves to almost complete death of the planetary life system and ourselves with it…

The ‘fiddling whilst Rome burns’ analogy comes to mind… we know the atmosphere is disturbed, we know we are disturbing the sea circulation…. it really is time that all these things were reducing, not accelerating in positive feedback already ,out of control ,as the figures indicate they are …

it is not time for another five years research before acting , it is time to mobilise everyone on the planet to change our way of life [one of the biggest ‘inertias’ in the system is humanity’s reluctance to change and learning time of new ways] …

It is seriously time to stop playing brinkmanship with existence of life on earth …and that is the thing we are gambling with against what is currently, but briefly a fairly small expense in best prudent insurance now [compared to massively increasing cost as time goes on, until no amount of money can save the ecosystems and us at a time which may easily be not far ahead , some say it is here already … there is absolutely no justification for risking all life on this planet for even massive expense, but we may well have a tiny window for doing it cheaply whilst the seas are somewhat alive … their death is not linear in time either …

We simply cannot have time for the mistake some dozen groups are playing with of just creating algal blooms which must then die , depriving the ocean of oxygen and with no great sequestration of CO2 to deep deposits or even guarantee that more co2 will not be released long term…

It is a crude sledgehammer approach where a hundredth of the amount of iron used could be chelated and fed in slow-release to the oceans to let the ecosystems expand, saving the seas and sinking truly massive amounts of CO2 into living biomass as the seas exponentially grow back to life UNDER OUR CONTROL and monitoring…

We even get vastly more food out of the process to offset the cost , enough to feed all people at last and at low cost , and off-setting the crippling loss of fertility of the land from modern farming methods…

If we all plant trees on our land , we can do much the same on the land too…

A serious look at the motor car shows that we would actually live vastly healthier lives without it and its pollution even without the massive contribution stopping using petrol and diesel cars would be to bringing things under control… this really is a win-win situation , a no-brainer … helping the earth and improving our quality of life at the same time…

Why are people not doing this? Do they not know yet? It seems even politicians mostly do not know that we are accelerating down the slippery slopes already , nor appreciate the extent of the damage , so how can the people ?

I just do not understand either how when we know that we don’t know all that could go wrong ,that we don’t play prudent and safe, extra-cautious until we do know , when we are playing for stakes of almost all life on earth, our own existence…

We are not then even considering the worst case scenarios and then maximising the chance of avoiding them, but why not? Since we all die in those cases, surely they are to ones to consider and ensure we maximise chances of avoiding them …

What we have at present i think is that even the best policy on the table is of somewhat less than 50% chance of keeping below 2C … but 2C is the point where some believe thermal run-away sets in… that makes no sense then at all as a policy, we want a close to zero chance of getting to that 2C point, not for it being more likely than not!

Again, methane release in the sea is being reported off South America, let us hope that it is only very local vulcanism or sea-bed shift , because if it is not we likely are too late to stop the ‘clathrate gun’ being triggered by ocean current changes kicking it off by merely LOCAL temperature rise over massive methane hydrate deposits … caused by just any ocean current shift with no average temperature rise of the earth needed to make it kick in…

I just do not get the confidence that men imagine that we can control this whenever we like , we really do not know that!

and the cost of doing so when we finally do so is exponentiating as we speak , what point is there at all in not doing all that can be done now, immediately ???

Equally we cannot just sit around and let the seas die, if we let 50% of species die off on the planet currently predicted , then it doesn’t stop there! … take any key organ out of our body and the whole dies, lose any key species and the ecosystem dies , almost all of it , and then we ourselves cannot survive that… the ecosystem that feed us will be committed to death long before v50% of species are extinct … putting it as percentage is misleading, this is NOT a linear process at all,not even close …

How can mankind not be working flat out to absolute first priority to minimise the chance of that, by every single method we know …I just don’t understand our complacency at all … we pride ourselves on intelligence , but this matter makes people dumb as rabbits caught in the headlights , standing inactive in the path of an approaching truck…

There is so much we can get going on immediately to get things moving back toward control, out of positive feedback and it just isn’t even beginning to happen… instead we are not even aiming to give ourselves half a chance to avoid pushing nature to the edge where there is no return…

It is seriously less than imprudent, it is irrational in extreme to play brinkmanship with an unknown edge of certain heat-death of our world … and we do know that we are currently accelerating toward it …

The oceans are understaturated with regards to CO2, always have been, always will be. Check back in geologic time, you will find that even CO2 atmospheric contents of 6000 ppm and more have been efficiently and quickly (geologically speaking) removed via the bicarbonate ion and massive CaCO3 precipitation when the balance is needed. There are hundreds of thousands of feet of naturally sequestered CO2 in limestone around the world. That is still happening and will continue, that is part of the natural cycle and thus the current short term, miniscule variances are nothing to get worried about. You people do need to get some earth science education.

One question I’ve been confused about. In temperate regions, like where I live, a deforested area is quickly grown over with a profusion of herbaceous species, and the forests tend to naturally reseed. What is the net effect on atmospheric CO2 in these areas?

[Response: Carbon is released as a forest is cut, perhaps slowly as the wood decays or quickly if it is burned. Then when it grows back, carbon is taken back up. Eventually as the forest reaches climax you are back where you started. David]

I’ve had a lot of fun recently with my tiny (and unofficial) slice of the 2007 Nobel Peace Prize awarded to the Intergovernmental Panel on Climate Change (IPCC). But, though I was one of thousands of IPCC participants, I don’t think I will add “0.0001 Nobel Laureate” to my resume.

The other half of the prize was awarded to former Vice President Al Gore, whose carbon footprint would stomp my neighborhood flat. But that’s another story.

Large icebergs in the Weddell Sea, Antarctica. Winter sea ice around the continent set a record maximum last month.
Both halves of the award honor promoting the message that Earth’s temperature is rising due to human-based emissions of greenhouse gases. The Nobel committee praises Mr. Gore and the IPCC for alerting us to a potential catastrophe and for spurring us to a carbonless economy.

I’m sure the majority (but not all) of my IPCC colleagues cringe when I say this, but I see neither the developing catastrophe nor the smoking gun proving that human activity is to blame for most of the warming we see. Rather, I see a reliance on climate models (useful but never “proof”) and the coincidence that changes in carbon dioxide and global temperatures have loose similarity over time.

There are some of us who remain so humbled by the task of measuring and understanding the extraordinarily complex climate system that we are skeptical of our ability to know what it is doing and why. As we build climate data sets from scratch and look into the guts of the climate system, however, we don’t find the alarmist theory matching observations. (The National Oceanic and Atmospheric Administration satellite data we analyze at the University of Alabama in Huntsville does show modest warming — around 2.5 degrees Fahrenheit per century, if current warming trends of 0.25 degrees per decade continue.)

It is my turn to cringe when I hear overstated-confidence from those who describe the projected evolution of global weather patterns over the next 100 years, especially when I consider how difficult it is to accurately predict that system’s behavior over the next five days.

Mother Nature simply operates at a level of complexity that is, at this point, beyond the mastery of mere mortals (such as scientists) and the tools available to us. As my high-school physics teacher admonished us in those we-shall-conquer-the-world-with-a-slide-rule days, “Begin all of your scientific pronouncements with ‘At our present level of ignorance, we think we know . . .'”

I haven’t seen that type of climate humility lately. Rather I see jump-to-conclusions advocates and, unfortunately, some scientists who see in every weather anomaly the specter of a global-warming apocalypse. Explaining each successive phenomenon as a result of human action gives them comfort and an easy answer.

Others of us scratch our heads and try to understand the real causes behind what we see. We discount the possibility that everything is caused by human actions, because everything we’ve seen the climate do has happened before. Sea levels rise and fall continually. The Arctic ice cap has shrunk before. One millennium there are hippos swimming in the Thames, and a geological blink later there is an ice bridge linking Asia and North America.

One of the challenges in studying global climate is keeping a global perspective, especially when much of the research focuses on data gathered from spots around the globe. Often observations from one region get more attention than equally valid data from another.

The recent CNN report “Planet in Peril,” for instance, spent considerable time discussing shrinking Arctic sea ice cover. CNN did not note that winter sea ice around Antarctica last month set a record maximum (yes, maximum) for coverage since aerial measurements started.

Then there is the challenge of translating global trends to local climate. For instance, hasn’t global warming led to the five-year drought and fires in the U.S. Southwest?

Not necessarily.

There has been a drought, but it would be a stretch to link this drought to carbon dioxide. If you look at the 1,000-year climate record for the western U.S. you will see not five-year but 50-year-long droughts. The 12th and 13th centuries were particularly dry. The inconvenient truth is that the last century has been fairly benign in the American West. A return to the region’s long-term “normal” climate would present huge challenges for urban planners.

Without a doubt, atmospheric carbon dioxide is increasing due primarily to carbon-based energy production (with its undisputed benefits to humanity) and many people ardently believe we must “do something” about its alleged consequence, global warming. This might seem like a legitimate concern given the potential disasters that are announced almost daily, so I’ve looked at a couple of ways in which humans might reduce CO2 emissions and their impact on temperatures.

California and some Northeastern states have decided to force their residents to buy cars that average 43 miles-per-gallon within the next decade. Even if you applied this law to the entire world, the net effect would reduce projected warming by about 0.05 degrees Fahrenheit by 2100, an amount so minuscule as to be undetectable. Global temperatures vary more than that from day to day.

Suppose you are very serious about making a dent in carbon emissions and could replace about 10% of the world’s energy sources with non-CO2-emitting nuclear power by 2020 — roughly equivalent to halving U.S. emissions. Based on IPCC-like projections, the required 1,000 new nuclear power plants would slow the warming by about 0.2 ?176 degrees Fahrenheit per century. It’s a dent.

But what is the economic and human price, and what is it worth given the scientific uncertainty?

My experience as a missionary teacher in Africa opened my eyes to this simple fact: Without access to energy, life is brutal and short. The uncertain impacts of global warming far in the future must be weighed against disasters at our doorsteps today. Bjorn Lomborg’s Copenhagen Consensus 2004, a cost-benefit analysis of health issues by leading economists (including three Nobelists), calculated that spending on health issues such as micronutrients for children, HIV/AIDS and water purification has benefits 50 to 200 times those of attempting to marginally limit “global warming.”

Mr. Christy is director of the Earth System Science Center at the University of Alabama in Huntsville and a participant in the U.N.’s Intergovernmental Panel on Climate Change, co-recipient of this year’s Nobel Peace Prize.

[Response: Mr. Christy is the guy who made a sign error in his analysis of satellite temperature records, with the result that satellites didn’t show the warming measured on the ground. This was a big argument in the denialist quiver until Mears cleaned up the mess. David]

I’m not sure whether it will help or hinder. As the oceans rise the new coast of the entire world will be in a constant state of active erosion as the new surf zone and the hills adjoining the sea seek to find stability at the soil’s angle of repose measured from the local bedrock at the then-current sea level. Thus until the sea rise is done – all ice melt and thermal expansion complete – the ocean in coastal waters will be carrying huge volumes of suspended and re-suspended earth.

This will certainly be bad for all coastal-breeding fish, but on the other hand it may add some useful minerals to the mix. Probably not much calcium (so it’s bye-bye shell fish for those of us who gather it in the shallow coastal waters), but it could provide a huge chemically active surface area (like adding activated carbon or bentonite) in the mixing zone that will eventually settle just off shore.

I would also like to ask about the biological impacts. Most of this discussion is about physics/chemistry. However we do know the biological cycle is important too. Has it been quantified at all? Is the increasing acidity causing a slowdown in formation of carbonate shells? Is the balance between photosynthesis and respiration being affected at all? Is there any data on this, or even a way to determine how to measure these effects – perhaps by isotopic measurements?

#25 [net effect] While herbs appear to grow faster than trees do, a standing crop of mature trees will hold vastly more carbon in biomass than will grasses and herbs over the same area. Trees can sequester carbon for over a hundred years, if allow to stand, while herbs and grasses will release any carbon they do take up in something like a single year (annuals) and a few years or a decade for larger, more woody herbs. Needless to say, it takes several decades for today’s seedling to uptake the same amount of carbon that was release when an earlier mature tree was cut out and removed (assuming it burned or was allowed to rot.) So that leaves us having to deal with that much carbon release into the atmosphere at a time when we can least afford it.

BTW, a tree removed from a forest and sawn into lumber for construction is (aside from the sawdust and leaves) still sequestered carbon. Our wood framed houses, if fated to stand for a hundred years, will keep that carbon out of the atmosphere AND allow more trees to grow where the former ones stood. While I am not a fan of lumber mills, this logic is hard to escape and in the run-up to a global catastrophe we need to look in all fruitful directions. Thus we should be making more structures out of wood and fewer out of metal, plastic and cement (the latter of which is a famous source of CO2) though this might have the net effect of spreading us out more because very tall buildings are less feasible. I can further imagine wooden cars, coaches and the like, wood-plank sidewalks instead of asphalt or cement, homes made entirely of wood including the foundation (as treated piers) and etc and so forth. Essentially, a forest under foot. In fact in a highly sustainable future the creative utilization of naturally occurring materials, many being carbon-based, will be the rule rather than fanciful speculation.

[Response: On the other hand, grasslands tend to sequester more carbon in soils, so the overall difference in carbon storage between forests and praries is smaller than you’d think. David]

I too would like an answer to Shannon’s question #2 (and rephrased #24). As another layman, it seems as if real world data is far ahead of even the most pessimistic forecasts.

Much has been made of the supposedly unreliability of climate models by climate-change-deniers. On current evidence I am beginning to agree with them, but for totally opposite reasons.

If the data quoted in this article is supported by other papers (and I understand this important qualification), will we have to wait another 5 years before the IPCC can publically acknowledge this? If so the words “fiddling” “Rome” and “burn” all come to mind…

[Response: Models of past climate changes, such as Dansgaard-Oeschger events or sea level increases, tend to underpredict somewhat the severity or the extent of the events. My opinion is that the IPCC forecast is a best-case scenario, in that there are no surprises. David]

So am I correct that the most recent 2007 IPPC report does not take into account this development? If not shouldn’t they redo their calculations lickedy split before everyone’s lured into a relatively false sense of security? As for me Ive heard enough, im stocking up on processed foods.

[Response: There’s a pretty wide range of atmospheric CO2 trajectories covered in the various scenarios. A weakening of natural carbon sinks would tend to leave us on the high side of the projected atmospheric concentration given some rate of emissions. And of course the emissions are higher than were projected also. So I guess this puts us at a high end of the projections, but I don’t think it’s a totally new ball game. David]

I suspect that the acid buildup is going faster than lime addition, plus warming. Oldtimers who fish at about Latitude 45 South don’t report windier weather but they do report more warm water fish species. Some believe it has been more cloudy than usual. A couple of speed yachting attempts (q.v. Bullimore) following the Roaring Forties were cancelled due to lack of wind. This alleged wind increase must be closer to the Antarctic.

I guess a slight change per square metre in ocean flux is more important than terrestial because of the larger areas.

The UNEP Report GEO4, just published, quotes in Figure 2.19 levels for (2-way) anthropogenic CO2 fluxes between ocean and atmosphere which seem remarkably high compared to the natural background fluxes and also almost 3 times the level of fossil fuel/cement emissions. Is this authoritative data? If so, why does this effect happen and might it change our view of oceanic sink reliability?

[Response: I don’t have the report in front of me, but carbon exchange fluxes with the land and with the ocean are much larger than the net fluxes from CO2 release or invasion. It makes it harder to measure and understand the net fluxes, but exchange is otherwise not so relevant to our situation. David]

Walt Bennett – “What it means to me is: somebody is going to figure out how to extract CO2 from the atmosphere, because it is too late for any other solution.”

If I were king, I’d put every available person (non-violent prisoners, the unemployed, anyone else that wants to help) to work planting trees, mixed forests of a draught resistant species, everywhere lacking forests presently. Billions of trees will take up some of the excess carbon and create habitat for some wildlife. These trees will prove the old cliche “rain makes trees, trees make rain.” It might not work… does someone have a better idea?

Uncontrolled technology has gotten our civilization to this unsustainable place. Only nature and the passage of time can fix things, either for we humans or for whatever life remains after the mass extinction that’s sure to come amazingly soon.

But I’m not king at all, more like a fly in boxcar on a train with no engineer or brakes screaming down from the mountains to cross a river where the bridge has washed out, while others on the train insist we’re parked at a station.

I think it’s safe to say that it’s freaking hard to determine the kinetics of reactions in situ and especially when living organisms are involved. There are several good links above, especially abut the pure equilibrium chemistry, I’ll just ad some about the “biological pump” and such below for the interested.

Really a question arising from the response to #6: will limestone and chalk coastlines start to dissolve noticeably faster as the ocean acidifies and, if so, will that have a noticeable feedback on the amount of CO2 in the ocean and atmosphere?

[Response: I don’t think the excess CaCO3 dissolution would be noticable like the fizz of an alka-seltzer, but if a large fraction of the fossil fuel is burned, there will be a worldwide hiatus in the deposition of CaCO3 on the sea floor. This time interval would be marked in sediment cores of the future by a layer of clay, like in the Paleocene Eocene thermal maximum event 55 myr ago. David]

A very small notation rant to go with the SI one in this thread. pCO2 is awful, precisely because you see it in expressions with pH and pKa so the first thing you think of is -log[CO2]. How about changing over to Pco2 or some such. The old lit has bushels and pecks but that is no reason to continue using them, and this is from a kcal guy.

[Response: Yeah, if we had it to do over again, I’d stay away from Gtons also, as a mass unit, rather than dealing with moles like proper chemists. Oh well. David]

This simple statement begs several questions. (1) What are the technologies. (2) Where have they been implemented. (3) Where are the data that validate the reduction in emissions. (4) What are safe levels for emissions. (5) What were the costs for implementing the proven technologies. (6) What are reasonable costs. (7) Where are the data that validate that the emission levels from the implemented technologies are safe.

While this comment will very likely be considered off-topic note that the original poster made the statement. And more importantly, why are such statements given a pass relative to the level of validation required for statements about the science?

[Response: It’s all in the Working Group III report of the IPCC, you can download all 1350 pages and read about it if you like. David]

We have seen methane levels remain flat recently. However, the amount of anthropogenic methane emissions have actually increased within the past few years as the result of the ramping-up of China’s economy. The difference has been the drying out of the lower latitude wetlands. The formation of methane is an anaerobic process which requires wet conditions.

Likewise, we have seen more methane being produced as the result of thawing permafrost, but only during the wetter years. However, we are supposed to see increased precipitation in the subpolar regions, and temperatures are supposed to rise there more than at the lower latitudes. The further up the warming takes the above freezing-temperatures for more months out of the year, the denser the pockets of permafrost. Which as usual means the further we take this, the further it will go – with compounded interest.

In Sweden we actually have the biggest mining company trying to fertilize the forest and optimize other parameters so that we would increase growth. Then they want to count that in as a carbon sink to draw from their CO2 output. It’s actually at research stage (academic and all) but I’m sceptic… one part not so well studied is how the sewage sludge used to fertilize the forest interact with the other parts of the forest. Another if enough sludge exists close enough to make it profitable…

The change being the ocean’s diminished ability to absorb CO2.This whole topic sounds a lot like a surprise element, perhaps like the North Atlantic Oscillation undergoing change in the near future, or a sizable chunk of real estate from Antarctica falling into the sea, ahead of schedule. It points to the need to take early,effective and perhaps draconian measures to mitigate AGW.

Re 28. It is sad to see John Christy let himself be used as a mouthpiece by the apologists of complacency such as the Wall Street Journal, Lomborg et al. Christy would have us believe that because we have much to discover we know nothing, and this is a fallacy that verges on mendacity. Worse, to allege that there are many scientists attributing every event of severe weather to climate change is simply a baldfaced lie. To allege that it is more difficult to predict climate than to predict weather is indicative of either extreme ignorance or mendacity. And finally to allege that those who advocate addressing climate change are condemning the third world to poverty is the biggest lie of all. I have said many times that mitigating climate change and facilitating development are two sides of the same problem–that of developing an economy that is both ecologically and economically sustainable.
I have to say that I am disappointed with Dr. Christy’s elastic attitude toward the truth. Perhaps he should look at what the scriptures of his holy book have to say about mendacity.

“What it means to me is: somebody is going to figure out how to extract CO2 from the atmosphere, because it is too late for any other solution.”

This can be accomplished through reforestation and organic agriculture, both of which have numerous other benefits.

Dan Hughes wrote:

“This simple statement [‘The technology exists to cut CO2 emissions to safe levels at reasonable cost’] begs several questions. (1) What are the technologies. (2) Where have they been implemented. (3) Where are the data that validate the reduction in emissions. (4) What are safe levels for emissions. (5) What were the costs for implementing the proven technologies. (6) What are reasonable costs. (7) Where are the data that validate that the emission levels from the implemented technologies are safe.”

The ASES report concluded that full application of existing energy efficiency and renewable energy technologies (wind power, biofuels, biomass, photovoltaics, concentrating solar power, and geothermal power) could reduce US carbon emissions by 60 to 80 percent by mid-century, which is in line with what mainstream climate science indicates will be needed to keep CO2 levels below 450 ppm, which is generally considered to be the level below which we can prevent “dangerous” climate change.

The report concluded that full application of existing energy efficiency technologies alone would “prevent our carbon emissions from growing over the next 23 years, even as our economy grows”; 57 percent of total reductions would come from energy efficiency improvements and 43 percent from expanded use of the six renewable technologies examined.

Re #42: [This simple statement begs several questions. (1) What are the technologies. (2) Where have they been implemented…]

That’s a question that’d require at least a book to answer in full. I’ll agree that “reasonable cost” is subjective, and AFAIK there’s no solid answer for “safe levels” except zero. But to make a start on the laundry list of CO2-reducing technology:

Magnus, thanks for the warning about that notion. Sewage sludge is not a particularly good material to use for fertilizer. Heavy metals, antibiotics, and hormone mimics — sewage systems worked before modern technological pollution got bad, but they don’t remove the new bad stuff at all. And even clean sewage is loaded with viruses. Talk about stuff that ought to be going into deep geological sequestration!